The term “deep hole” relates to a hole having a ratio of a hole length to a hole diameter that is greater than 5, such as a hollow spindle hole and a hydraulic valve hole. Some of these holes require high machining accuracy and surface quality, and sometime the materials to be machined have poor machinability. In the process of the deep hole machining, the operator is not able to directly inspect the conditions of the machined part and the cutter, but has to listen to the sound of cutting, observe the conditions of chips, tactually feel the vibration condition and the temperature of the workpiece and observe the meters such as oil pressure gauge and electric meter, so as to make experimental judgement on the conditions of the cutting process. All the above methods is incapable of detecting the axis deviation inside the deep hole, such that a continuous dynamic detection on the straightness of the deep hole part is not achieved and therefore inaccuracy occurs. Also, the cutter for the deep hole process has poor rigidity and difficulty in removing chips, which greatly impinge the straightness of the deep holes and therefore axis of these deep holes is liable to skew. Up to day, there are no simple and practical deep hole machining on-line deviating correction device and detection means used prior to the correction.